Coulomb Force (Static) Questions Part 1

1. On the Gizmo, click Show force vector for charge A and Show force vector for charge B. The forces on each charge are represented by the purple and green arrows. The charges of each particle, q_A and q_B, are shown below the particles. Check that each charge is set to 10.0 • 10⁻⁴ C.

a. Observe the arrows representing the Coulomb force between the charges. Do you think this represents an attractive or a repulsive force?

1A answer: I think that charge A and Charge B represent a repulsive force because they are repeling one another (moving in opposite directions which makes them a repulsive force.

b. Change the charge of particle A (q_A) to -10.0. (To change q_A, type a value in the field next to the slider and hit Enter.) You now have a positive and a negative charge (as in the "hair and balloon" experiment). What effect does this have on the arrows? Is this an attractive or repulsive force?

2A answer: When I changed the qa: number from 10 to -10 on charge A the arrows changed to pointing on each other. So now the force is an attractive force.

c. Change the charge of particle B to -10.0. What kind of force is experienced by two negative charges? You can model this by rubbing two balloons and slowly bringing them together.

1c answer: When I changed the B charge from 10 to -10 now the both charges where the same they repelled from each other making it a repulsive force again.

D. Change the charge of particle A back to +10.0. As a rule, what kind of force will result when charges are opposite? What kind of force will result when the particles have the same charge?

1d answer: When the charges are the same the force will repeal but when the forces are opposites then they will attract.

2. Change the charge of particle A to 0.0. A particle with zero charge is neutral.

2a: What happens to the force arrows?

2a answer: when I changed the charge A to 0.0 and the B was the same the lines disappeared and where showing as dots.

2b: What is the force between a charged particle and a neutral particle? Try several values for particle B to see if this is always true. (Note: In reality, neutral objects are composed of charged particles. If you bring a charged object near a

neutral object, the charged particles within the neutral object will rearrange themselves in a process called polarization. This results in an attractive force between the charged object and the neutral object that is not shown in the Gizmo.)

2b answer: When I changed the values for charge B, the charges still stayed Nutrial because one of them has no charge.

3. To see the magnitude of the Coulomb force, click Show vector notation for particle A and particle B. The magnitude of the force (in Newtons) is written |F_A| or |F_B|. Set each charge to 10.0 • 10⁻⁴. Click Show distance and Show grid, and drag the particles together until the distance between them is 30 m.

3a: What is the Coulomb force on particle A?

3a answer:

1. What is the force on particle B?
2. Drag the particles around. Are the forces on particle A and B always equal to one another?